Vegetable oils are typically oils that have been pressed or extracted, such as from a vegetable source. Many vegetable oils contain some form of phosphatides (e.g., hydratable or non-hydratable), commonly known as gums. For instance, soybean oil contains about 1-3%, corn oil 0.6-0.9%, sunflower oil 0.5-0.9%, and canola oil (crude) 1-3% of gums.
The primary components to be removed during vegetable oil refining (degumming) are free fatty acids (FFAs) and phospholipids contained in the oil. Such components are usually removed by applying an acid treatment and caustic soda treatment in an oil neutralization step. Neutralization is an important step in the chemical refining of vegetable oils for removing FFAs. Traditionally, FFAs are treated with caustic soda (NaOH). The neutralization reaction produces soaps or soapstock which are separated from the oil to form a purified oil product.
In addition to the formation of soapstock being a drawback, separation of the soapstock can result in oil losses. For instance, FFAs are generally removed during neutralization as sodium soaps, but desirable neutral oil is also entrapped in the emulsion formed during the neutralization process due to the soapstock's emulsifying effect. The trapped neutral oil is removed along with the soap during centrifugation.
Some improvements have been introduced in oil treatment processes. Improved mixing of chemicals during caustic soda and acid treatment using hydrodynamic cavitation reactors, high-pressure valve type homogenizers, and compression-decompression devices have been suggested to lower consumption of acids and alkali, and to improve the efficiency and oil yields in vegetable oil refining processes. Such processes can be found in, for example, U.S. Pat. Nos. 8,911,808; 8,945,644; 9,410,109; 9,453,180; 9,556,399; 9,765,279 and 9,845,442.
To reduce separation losses, the process design should minimize production soapstock during the neutralization operation. The present invention provides solutions for improving oil degumming processes that overcome the disadvantages of soapstock formation.